Theoretical study of endohedral C36 and its dimers.

It is found that atoms of lithium and carbon can be encapsulated in C(36) on the basis of the calculation of their encapsulation energies using density functional theory. Specifically, they can be encapsulated in C(36) better than in C(60) despite the smaller (70%) cavity size of the former. In C@C(36), the encapsulated carbon atom forms covalent bonds with the carbon atoms of the cage, which is in contrast with the case of N@C(60.) Two isomers are expected to be in an equilibrium which involves spin quenching and generation. Li@C(36) and C@C(36) are expected to exist in the form of dimers with nonendohedral fullerenes, i.e., as Li@C(36)-C(36) and C@C(36)-C(36). Three stable isomers were found for the former (A, B, and C). Equilibrium between A and C as well as that between B and C is accompanied by spin transfer between two fullerene units, while that between A and B is not. The two stable isomers in C@C(36)-C(36) form an equilibrium accompanied by spin quenching and generation, allowing the dimer to be potentially useful for molecular devices.